Like most of the Acadians of the time, they were probably trying to stay one step ahead of the British. Have you ready any histories of PEI?
The Acadians left the mainland NB/NS for the island areas of PEI and Cape Breton, Magdalen Islands and St-Pierre & Miquelon to escape their pursuers.
There was so much back and forth movement at the time, it is truly difficult to keep track of everyone and where they were.The British expelled the last of the Acadians from PEI in 1758 on the death ships Duke William and the Violet for Europe.These two sank in the crossing, drowning many Acadian ancestors and their families. Obviously, Francois and Anne were not among that number, probably having sailed off to Cape Breton Island for a stint before returning to PEI.They obviously did not go to Miquelon as they are not in the 1767 census.When David Higgins started to gather Acadians for tenancy of the lands in Montague, they were probably among that number.A document Stephen White found in the Scottish Archives names several of the heads of families who were there including, Nicolas and Anne Arseneau, Charles & Madeleine Boudreau, Pierre & Cecile Lapierre, Gregoire Maillet, etc.
The reason these kids left PEI is because they were tenant farmers for agent David Higgins, whose efforts ended in failure, and the settlement closed, leaving them without subsistence.
When his settlement failed at Montague, the Acadians left again for the Magdalens and Cheticamp.That's about all I know.If you're anywhere near PEI, you might want to write to/ask Georges Arsenault, the local historian from there, or check with the Acadian Museum in Miscouche for other biographical references.Also, Henri Blanchard's books are helpful.